public override List<Node> getResultingNodesToAddToFrontier(Node nodeToExpand,
Problem problem)
{
addToFrontier.Clear();
// add the node to the explored set
explored.Add(nodeToExpand.getState());
// expand the chosen node, adding the resulting nodes to the frontier
foreach (Node cfn in expandNode(nodeToExpand, problem))
{
Node frontierNode = frontierState[cfn.getState()];
bool yesAddToFrontier = false;
// only if not in the frontier or explored set
if (null == frontierNode && !explored.Contains(cfn.getState()))
{
yesAddToFrontier = true;
}
else if (null != frontierNode
&& null != replaceFrontierNodeAtStateCostFunction
&& replaceFrontierNodeAtStateCostFunction.Compare(cfn,
frontierNode) < 0)
{
// child.STATE is in frontier with higher cost
// replace that frontier node with child
yesAddToFrontier = true;
// Want to replace the current frontier node with the child
// node therefore mark the child to be added and remove the
// current fontierNode
removeNodeFromFrontier(frontierNode);
// Ensure removed from add to frontier as well
// as 1 or more may reach the same state at the same time
addToFrontier.Remove(frontierNode);
}
if (yesAddToFrontier)
{
addToFrontier.Add(cfn);
frontierState.Add(cfn.getState(), cfn);
}
}
return addToFrontier;
}
}
